I have three files: Main.py, Game.py, and CreateDisplay.py . Obviously Main is going to be the main file where everything is going to run from. This is my first project that i have split the code into separate modules and i am having problems.

The problem i am having is that when the display is made, the background isn't filled with white, its black, and no matter what i do to the variable 'WHITE' it stays black.

Why are you importing CreateDisplay into Main.py? You are not using it. Anyway, I suspect the problem is you are trying to use python modules like C++ headers. You import pygame three times, once in each file. Each file will have a separate, distinct pygame object (or whatever it is). What you should do is create your stuff in the main script, and pass it to the other scripts. But for simplicity I suggest you stick to a single file for now.

“If I understand the standard right it is legal and safe to do this but the resulting value could be anything.”

Why are you importing CreateDisplay into Main.py? You are not using it. Anyway, I suspect the problem is you are trying to use python modules like C++ headers. You import pygame three times, once in each file. Each file will have a separate, distinct pygame object (or whatever it is). What you should do is create your stuff in the main script, and pass it to the other scripts. But for simplicity I suggest you stick to a single file for now.

I've made many programs using one file and am doing my new project this way to learn how to properly do it. So I should only import pygame in Main.py?

As ultramailman mentioned, you initialized "WHITE" but never used it anywhere. The value is correct for a true white color, it just comes down to setting the color of the screen.

screen.fill(WHITE);

and after that you are going to want to make sure that you use pygame's flip method to properly display the screen.

pygame.display.flip();

I'm not sure why it isn't in the code sections above but i called for "DISPLAY" to be filled "WHITE" and it is not working. I combined CreateDisplay.py and Game.py, and added pygame.diplsay.flip() to the Game() definition and it works fine now. I assumed having pygame.display.update() in Main.py would be enough.

I've made many programs using one file and am doing my new project this way to learn how to properly do it.

Sometimes using one file is the proper way to do it, depending on how you are structuring the code. How complex your game is would also have a big impact on how the code is layed out. As Bacterius mentioned, you are using Python modules like C++ headers. Try and treat modules like their name implies for a "modular" design. A google search for "python idioms" may yield some useful information.